u/Wild_Neighborhood605

Part II could be found here: https://www.reddit.com/r/radon/comments/1sn8im2/ambient_rn222_adsorbed_on_activated_charcoal/

In short, I kept the sample from part II and remeasured it after 7 and 13 days respectively. The idea was that when Rn-222 decays, the sample activity and x-ray fluorescence will decrease, allowing to see the elusive Pb-210 peak at 46.5 keV better. This time I used the Radiacode 103 (for the main experiment the 103G was used) because its lower energy response is better suited for this.

I thing I got it.

This is the last part of this lengthy, but fun experiment.

Part II was posted here: https://www.reddit.com/r/Radiation/comments/1sn7dqh/ambient_rn222_adsorbed_on_activated_charcoal_part/

In short, I kept the sample from part II and remeasured it after 7 and 13 days respectively. The idea was that when Rn-222 decays, the sample activity and x-ray fluorescence will decrease, allowing to see the elusive Pb-210 peak at 46.5 keV better. This time I used the Radiacode 103 (for the main experiment the 103G was used) because its lower energy response is better suited for this.

I thing I got it.

This is the last part of this lengthy, but fun experiment.

Part II was posted here: https://www.reddit.com/r/Radiacode/comments/1sn79dg/ambient_rn222_adsorbed_on_activated_charcoal_part/

In short, I kept the sample and remeasured it after 7 and 13 days respectively. The idea was that when Rn-222 decays, the sample activity and x-ray fluorescence will decrease, allowing to see the elusive Pb-210 peak at 46.5 keV better. This time I used the Radiacode 103 (for the main experiment the 103G was used) because its lower energy response is better suited for this.

I thing I got it.

Got one of these lately and it turned out to be ever so slightly radioactive. Remains that fossilize in regions rich in uranium and thorium tend to accumulate them and become radioactive. In this case it is uranium as indicated by uranium progeny peaks of Pb-214 and Bi-214. Second images shows the spectrum in black and the background that was subtracted in red.

Got one of these lately and it turned out to be ever so slightly radioactive. Remains that fossilize in regions rich in uranium and thorium tend to accumulate them and become radioactive. In this case it is uranium as indicated by uranium progeny peaks of Pb-214 and Bi-214. Second images shows the spectrum in black and the background that was subtracted in red.

The latest addition to my Seiko collection. Love this piece. Yes, a departure from the classical Seiko diver design, but beautiful nonetheless. When I saw it in the store about a year go, I just had to have it. Spent the most time on wrist ever since.

6602-8050, summer of 1970. Unfortunately, the original beads of rice bracelet didn't survive.

A standard issue eastern block military compass from 1945. They were manufactured with radium paint until the first half of the 70's. Millions were made in several countries.

The spectrum was taken inside a shield with a Radiacode 103G.

This may get a bit long, so please bear with me or skip it if not interested.

In short, I'm interested in ambient Rn-222 adsorbed on activated charcoal (AC). In a previous experiment, I simply left a tray of powdered AC in a room for a few days and measured it, but the activity was rather low. This time I constructed a “sampling device”. I placed 45 grams of granulated AC (much less messy to work with) in a metal container drilled from both sides and capped with some non-woven fabric. I placed it on a laptop cooling pad (to force air through it), and set a timer to power it on a 6 hours on-2 hours off schedule. The first image shows the sampler (I know, the drilling is sloppy). I collected Rn for 24 days, moving the sampler to a different room once every 3-4 days. After that, the AC was transferred into LDPE zip-lock bags and measured with Radiacode 103G for approx. 75 hours. The image shows the activity after 75 hours of measurement, when taken out of the shield. Initially it was higher. The recorded parameters are outlined in the third image. For those who have followed my previous posts, the method is known. In short I record time, the whole sample activity, and this time, the count of Pb-214 peak at 352 keV. From the count data I extract the activity through a polynomial fit and determine half life for both the whole sample and from the fit. The assumption is that Pb-214 is in secular equilibrium with much longer living Rn-222.

I'd say, the results are not bad. Both methods give slightly shorter half-live of Rn-222 (3,82 days). The main reason IMO is some Rn-222 desorbtion during the measurement. Although the bags are sealed, Rn can slowly diffuse through LDPE.

This may get a bit long, so please bear with me or skip it if not interested.

In short, I'm interested in ambient Rn-222 adsorbed on activated charcoal (AC). In a previous experiment, I simply left a tray of powdered AC in a room for a few days and measured it, but the activity was rather low. This time I constructed a “sampling device”. I placed 45 grams of granulated AC (much less messy to work with) in a metal container drilled from both sides and capped with some non-woven fabric. I placed it on a laptop cooling pad to force air through it, and set a timer to power it on a 6 hours on-2 hours off schedule. The first image shows the sampler (I know, the drilling is sloppy). I collected Rn for 24 days, moving the sampler to a different room once every 3-4 days. After that, the AC was transferred into LDPE zip-lock bags and measured with Radiacode 103G for approx. 75 hours. The image shows one of the bags after 75 hours of measurement, just taken out of the shield. The recorded parameters are outlined in the third image. For those who have followed my previous posts, the method is known. In short I record time, the whole sample activity, and this time, the count of Pb-214 peak at 352 keV. From the count data I extract the activity through a polynomial fit and determine half life for both the whole sample and from the fit. The assumption is that Pb-214 is in secular equilibrium with much longer living Rn-222.

I'd say, the results are not bad. Both methods give slightly shorter half-live of Rn-222 (3,82 days). The main reason IMO is some Rn-222 desorbtion during the measurement. Although the bags are sealed, Rn can slowly diffuse through LDPE.

This may get a bit long, so please bear with me or skip it if not interested.

In short, I'm interested in ambient Rn-222 adsorbed on activated charcoal (AC). In a previous experiment, I simply left a tray of powdered AC in a room for a few days and measured it, but the activity was rather low. This time I constructed a “sampling device”. I placed 45 grams of granulated AC (much less messy to work with) in a metal container drilled from both sides and capped with some non-woven fabric. I placed it on a laptop cooling pad (to force air through it), and set a timer to power it on a 6 hours on-2 hours off schedule. The first image shows the sampler (I know, the drilling is sloppy). I collected Rn for 24 days, moving the sampler to a different room once every 3-4 days. After that, the AC was transferred into LDPE zip-lock bags and measured with Radiacode 103G for approx. 75 hours. The image shows the activity after 75 hours of measurement, when taken out of the shield. Initially it was higher. The recorded parameters are outlined in the third image. For those who have followed my previous posts, the method is known. In short I record time, the whole sample activity, and this time, the count of Pb-214 peak at 352 keV. From the count data I extract the activity through a polynomial fit and determine half life for both the whole sample and from the fit. The assumption is that Pb-214 is in secular equilibrium with much longer living Rn-222.

I'd say, the results are not bad. Both methods give slightly shorter half-live of Rn-222 (3,82 days). The main reason IMO is some Rn-222 desorbtion during the measurement. Although the bags are sealed, Rn can slowly diffuse through LDPE.

Finally got one. Spectrum is unmistakably uranium. On the third image the background is shown in red. Doing gamma spectroscopy at home is such a fun!

After I checked several pieces that were dead as doornails, I finally got one that is ever so slightly active. The spectrum is unmistakably uranium. Background (red in the third image) is subtracted.

I don't know if this is funny or sad, but these were the times...